Wong 2006.

Study characteristics
Methods	Parallel, randomised controlled trial
Participants	Setting: recruited from Northwestern University, Chicago, Ilinois, USA Sample size: N = 158 (N completers = 126) Participants' age not provided Inclusion criteria: healthy, parous (at least one previous vaginal delivery), term women with singleton, vertex pregnancies, scheduled for induction of labour 11 women from the PIEB group and 9 women from the CEI group were excluded for having delivered within 90 min of intrathecal analgesia. 10 women from the PIEB group were excluded for exceeded pump occlusion limits. 2 women were excluded for VAS > 10 mm 10 min after intrathecal injection
Interventions	AMB (n = 63): PIEB pump delivered a 6‐mL bolus at a rate of 400 mL/h every 30 min beginning 45 min after administration of the intrathecal dose The PCEA pump was programmed to deliver 5 mL patient‐activated boluses with a lockout interval of 10 min and a per hour maximum of 15 mL. The participant was instructed on the use of the PCEA pump and was told to push the button whenever she felt uncomfortable. If the parturient felt she had inadequate analgesia after having activated the PCEA bolus twice in a 20‐min period an anaesthesiologist administered manual boluses of bupivacaine 1.25 mg/mL (5 mL to 15 mL) until the VAS was < 10 mm BI (n = 63): the CEI pump delivered a continuous infusion at 12 mL/h beginning 15 min after the intrathecal dose The PCEA pump was programmed to deliver 5 mL patient‐activated boluses with a lockout interval of 10 min and a per hour maximum of 15 mL. The participant was instructed on the use of the PCEA pump and was told to push the button whenever she felt uncomfortable. If the parturient felt she had inadequate analgesia after having activated the PCEA bolus twice in a 20‐min period an anaesthesiologist administered manual boluses of bupivacaine 1.25 mg/mL (5 to 15 mL) until the VAS was < 10 mm
Outcomes	Rate of breakthrough pain with need for anaesthetic intervention Rate of caesarean delivery Rate of instrumental delivery Duration of labour LA per hour Maternal satisfaction
Notes	Study dates: June 2003 to April 2005 Funding sources not declared No conflict of interests declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation by computer‐generated random number sequence: Quote: "A sequentially numbered opaque envelope containing the group assignment (computer generated random number sequence) was opened by the unblinded anesthesia researcher at the time of randomization."
Allocation concealment (selection bias)	Unclear risk	Allocation concealment by sequentially numbered opaque envelopes, but it was not stated that envelopes were sealed: Quote: "A sequentially numbered opaque envelope containing the group assignment (computer generated random number sequence)..."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants and other personnel were blinded: Quote: "The subject and other study personnel were blinded as to group assignment."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessors were blinded: Quote: "The subject and other study personnel were blinded as to group assignment."
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low attrition: no dropouts
Selective reporting (reporting bias)	Low risk	All a priori outcomes reported based on published protocol
Other bias	Low risk	Appears to be free of other sources of bias. Sample size calculation: sample size would be required to avoid a type II error at 0.05 and power of 0.80. 30 additional participants were included in the randomisation to allow for anticipated exclusion of participants from data analysis

AMB: automated mandatory bolus; ASA: American Society of Anesthesiologists; BCI: basal continuous infusion; BI: basal infusion; BMI: body mass index; CEI: continuous epidural infusion; CSE: combined spinal‐epidural; DPE: dural puncture epidural; LA: local anaesthetic; PCEA: patient controlled epidural analgesia; PIEB: programmed intermittent epidural boluses; VAPS: visual analogue pain scale; VAS: visual analogue scale..